Medical thermometers are typically used to facilitate the prevention, diagnosis and treatment of diseases, body ailments, etc. for humans and other animals. Doctors, nurses, parents, and other care providers use thermometers to measure a subject's body temperature. An accurate reading of a subject's core body temperature is needed for effective use and should be taken from the internal or core temperature of a subject's body. Several thermometer devices are known for measuring a subject's body temperature, such as, for example, glass, electronic, and ear (tympanic).
Tympanic thermometers are generally considered by the medical community to be superior for taking a subject's temperature. Tympanic thermometers provide rapid and accurate readings of core temperature, overcoming the disadvantages associated with other types of thermometers. Tympanic thermometers measure temperature by sensing infrared emissions from the tympanic membrane (eardrum) in the external ear canal. The temperature of the tympanic membrane accurately represents the body's core temperature. Further, it only takes a few seconds to measure a subject's temperature in this manner.
Known tympanic thermometers typically include a probe containing a heat sensor such as a thermopile, a pyroelectric heat sensor, etc. See, for example, U.S. Pat. Nos. 6,179,785, 6,186,959, and 5,820,264. These types of heat sensors are particularly sensitive to the eardrum's radiant heat energy. The accuracy with which the sensing probe senses the infrared radiation emitted by the eardrum directly corresponds with the overall accuracy, repeatability and usability of the tympanic thermometer. The sensing probe must be sensitive to the low level of infrared energy emitted by an eardrum while providing a high degree of accuracy, repeatability and thermal noise immunity.
In operation, a tympanic thermometer is prepared for use and a probe cover is mounted onto a sensing probe extending from a distal portion of the thermometer. The probe cover provides a sanitary barrier between the subject and the thermometer. A practitioner or other care provider inserts a portion of the probe having the probe cover mounted thereon into a subject's outer ear canal to sense the infrared emissions from the tympanic membrane. The infrared light emitted from the tympanic membrane passes through a window of the probe cover to the sensing probe. The window is substantially transparent to infrared radiation, thereby allowing infrared radiation from the tympanic membrane to pass through the probe cover to the heat sensing probe of the thermometer. Although an open window would be suitable for taking a temperature measurement, a film (e.g., a plastic film) having a thickness on the order of the wavelength of radiation in the far infrared range typically spans the window to provide a sanitary barrier between the subject and the probe.
The practitioner presses a button to cause the thermometer to take a temperature measurement. The microelectronics process electrical signals from the heat sensor to determine eardrum temperature and render a temperature measurement in a few seconds or less. The probe is removed from the ear canal and the probe cover discarded. A new probe cover is used each time the thermometer is used with a new subject to reduce the risk of cross-contamination (e.g., spreading of pathogens) between subjects.
The thermometer may be used many different times. In a hospital or other health care facility, for example, a thermometer may be used to measure the temperature of up to a few dozen subjects each day. Thus, the care provider needs a supply of probe covers to replace the used probe covers. A plurality of nested probe covers can be supplied to replace used probe covers, for example as shown in U.S. Pat. No. 5,088,834. The probe covers in a nested stack are held together by gravity and/or friction between adjacent probe covers. Nesting probe covers together in this way is efficient use of space, but it has disadvantages. For example, it may be necessary to manually handle the probe covers to separate them for attaching one of the probe covers to a thermometer probe. This is undesirable because it is possible that pathogens or other contaminants could be transferred to the probe covers during the handling. Further, the probe covers (particularly the film portions thereof) are thin and can easily be damaged when handled manually. If the damage results in rips or tears in the film, there is no sanitary barrier between the subject and the thermometer probe. Even if the damaged film is sufficiently intact to provide a barrier, distortions, wrinkling, and/or foreign substances can alter the way infrared radiation is transmitted through the film and can thereby decrease the accuracy of the temperature measurement.
Some of the foregoing problems can be overcome by supplying a plurality of probe covers that are arranged side-by-side. For example, a care provider can carry a cassette comprising a plurality of probe covers releasably attached to a frame. One such cassette is disclosed in U.S. Pat. No. 4,662,360, the disclosure of which is incorporated herein by reference. The probe covers of the cassette (shown in FIGS. 8-10 of the '360 patent) are connected to the frame by two frangible stems. This approach has also been used by the FirstTemp Genius® tympanic thermometer system available from Tyco Healthcare of Mansfield, Mass.
The FirstTemp Genius® system comprises a tympanic thermometer and a holder that releasably holds the thermometer when it is not in use. The holder has a storage compartment for holding a probe cover cassette. The storage compartment has an opening and is configured to hold the cassette so the open ends of the probe covers are accessible through the opening. When the thermometer is received by the holder, the cassette stored in the compartment is underneath the thermometer. Thus, one cassette can be stored in the compartment without interfering with the holder's ability to hold the thermometer. Inside the storage compartment is a base defining a plurality of wells for receiving the releasably attached probe covers. A probe cover can be put on the thermometer probe by inserting the probe into one of the releasably attached probe covers. The force of insertion causes the frangible stems to break, thereby releasing the probe cover from its attachment to the frame before the probe cover is secured to the thermometer probe. The user continues to move the probe in the direction of insertion until a shoulder on the outside of the probe cover contacts the base at the opening to the well. The probe cover is finally attached to the thermometer probe by using the thermometer probe to push the probe cover shoulder against the upward facing part of the base surrounding its well to apply a securement force sufficient to secure the probe cover to the probe. The force required to secure the probe cover to the probe depends on several variables, including friction between the probe and probe cover, the force required (if any) to expand the probe cover to fit on the probe, and the force required (if any) for the probe cover to push one or more probe cover ejectors to retracted positions. As the thermometer probe is inserted into the probe cover, retention bumps on the inside of the probe cover slide past an annular ridge on the thermometer probe. The probe cover is retained on the thermometer probe by engagement of the retention bumps with the annular ridge and by friction between the probe cover and thermometer probe. Once the probe cover is on the probe, the thermometer is ready for use. After a subject's temperature is taken, the probe cover is removed from the thermometer probe and discarded.
In general, it is desirable to make as efficient use of the probe cover storage space in the holder as is practically possible. More efficient use of space could result in a smaller overall size of the thermometer system and/or increase the number of probe covers that can be supplied without re-stocking probe covers. Moreover, it is also desirable to make use of probe covers with tympanic thermometer systems as user friendly as possible. For example, some probe cover cassettes can be difficult to load in a holder because the releasably attached probe covers can swing out of alignment with the wells in the base of the holder. When this happens, the probe covers have to be manually realigned before they can be received in the wells, which is an inconvenience to the user and also makes it more likely that the probe covers will be contaminated. It is also desirable to provide users tactile and other sensory feedback to facilitate use of probe covers in a tympanic thermometer system.
Accordingly, there is a need for systems and methods for handling a supply of probe covers for use with a tympanic thermometer more efficiently and conveniently.